Above advice is good.
USED CAR CHECK
All the usual checks apply when buying a used/ cherished secand hand car. Check Coolant levels and Oil levels especially on the S3. Some cars have had issues with these two points.
Coolant should be between the min and max lines. If its above the max on a cold engine the owner might have had issues previously and this is the first thing Audi advise to do. Ie overfill. There is a fix for this now (apparently) from Audi but depends if car still has warranty. Some of the early cars are now out of warranty unless extended..(.63 /14/64 and soon 15 plate etc ).
Oil usage. Some cars like to sip oil, this is nothing to worry about necessarily but just be aware. Oil should be clean
Ask the owner about these two points especially.
The DSG should be smooth in all modes and aggresive in Dynamic. It might be a little lumpy for 2 mins until oil is upto temp but otherwise it should be perfect.
Engine/Turbo rattle/rustle. You may notice a slight rustle noise when the car is under light load. This is normal, Golf R and S3 and even 1.8 and standard 2.0 TFSI turbo engines emit this noise. Audi still working on a poential fix. But this is nothing to worry about.
Turbo - There was a batch of turbos which did have more chance of blowing. Manufacturing default etc. Do a forum search for numbers etc. Sorry I cant recall further info. But at 30k hopefully its all good by now. They tended to go pop pretty quick / early in life.
Service- S3 should be serviced yearly really or atleast have oil changed. Some cars were put on long life. So double check intervals and whats been done. Shorter more regular obviously better.
Other servicable items - Haldex / Auto DSG box service etc. Audi dont actually recommend a service on either of these two components until later in the cars life. However it would show good prevantative maintenance if atleast the Haldex oil was changed. Its one area that can causee potential issues on the 4WD Haldex system and people on the forum are looking at shorter service intervals to ensure the pump does not get blocked. Its a cheap thing to do, but can save you ££££. So worth looking at if you buy the car and its not been done. You can test the 4WD sustem relatively easy on a test drive. Basically you should have good traction even on greasy roads, even under full acceleration. If the traction light is flickering like mad on anything other than light acceleration its a potential warning sign ( presuming tyres are all good ).
Warranty work / Recalls - To my knowledge there have been no major recalls, but any previous issues with the car should have been sorted under warranty. If any have not ask why not. Could point to an ongoing problem?
Exhaust tips. All four should be clean ideally, the inner two soot up quicker but this will help you see if the current owner truly loves his cars. Its one area a lot of people just dont clean.
Wheels- Check for kerbing. £120 circa to fix as diamond cut edges if standard wheels. £50 for aquick glance test fix.
Tyres - All S3's if on 18 wheels generally came with Conti Sport 5 tyres. I would have thought these would been changed now and possibly twice by owner ( dependent on how car was driven ) so see what they have replaced them with. Conti Sport 6, Michelin PS3/4 or
Goodyear F1 Eagle Asy2/3 and Dunlop Sportmaxx are all highly rated tyres for the car. Many owners actually dont like the Conti Sport 5. I had no issues with mine but changed for the sake of curiosity when mine came up.
If you have VCDS ask to do a scan or take a £10 dongle with you from Amazon and perform a quick scan. You would be surprised what can flag up.
Ask the owner if they have completed any VCDS modifications? Popular items are - exhaust flaps/ alarm chirp/ windscreen wiper service etc. Once again I see this as nothing to worry about.
Remaps- Ask the owner if the car has ever had a ECU remap or DSG TCU map. These are not necasarily bad things but you should be aware of them. And if car has had a proper ECU map then even if flashed back to stock it may well trigger a TD1 flag due to ECU count changing. Audi will pick this up if the car needs major engine / turbo warranty work. (TDI flag).
Ring up the Audi garage where the car has been serviced - check records and ask about the car. Give them the VIN so they know you are serious and they might throw some more light on the car. U can do this with the owner/ without. As other have also suggested using these details will show you the factory spec and options. People also retrofit some options, with popular items, parking sensors, folding heated wing mirrors, reversing camera etc. Once again not an issue and only a benefit. Just make sure it all works and if OEM performs as it should in an integrated way.
No of owners - A car which is 3-4 years old could easily have several owners. This should not put you off or be a concern. ( example - 1st from new, 2nd owner after 1 year, 3rd owner had for last 2 years ) What I would look for is lots of owners and in a short period. That might point to a dog of a car.
I think you can tell a lot about the car from the owner. How its cared for, documentation on the car, and how they first drive the car. Step back and let them take the lead. Let your mind rule not your heart!!
All the best ... These cars dont have the same engine noise as the RS cars but they sure fly and are a very very pleasant place to be. A step above many other hot/ hyper hatches.
Hope all goes well for you
Regds
Jungle